I've heard that the Guerilla 22s are slightly bigger around than than their 13s, and thus bigger than a 3/5/7oz CO2 tank and too big for the RAP4 flexi M4 tank stocks. You might be able to get one of those basic plates to expand enough to fit, and if not the plate for a 9oz should fit. My generic 22ci is the same diameter as a 13, and fits the smaller stocks fine, but the place I got it from is no longer in business.